Comparative anatomy of the caudate nucleus in canids and felids: Associations with brain size, curvature, cross-sectional properties, and behavioral ecology.

The evolutionary history of canids and felids is marked by a deep time separation that has uniquely shaped their behavior and phenotype toward refined predatory abilities. The caudate nucleus is a subcortical brain structure associated with both motor control and cognitive, emotional, and executive functions. We used a combination of three-dimensional imaging, allometric scaling, and structural analyses to compare the size and shape characteristics of the caudate nucleus. The sample consisted of MRI scan data obtained from six canid species (Canis lupus lupus, Canis latrans, Chrysocyon brachyurus, Lycaon pictus, Vulpes vulpes, Vulpes zerda), two canid subspecies (Canis lupus familiaris, Canis lupus dingo), as well as three felids (Panthera tigris, Panthera uncia, Felis silvestris catus). Results revealed marked conservation in the scaling and shape attributes of the caudate nucleus across species, with only slight deviations. We hypothesize that observed differences in caudate nucleus size and structure for the domestic canids are reflective of enhanced cognitive and emotional pathways that possibly emerged during domestication.

Leading the transition to ethical human body sourcing in Africa: The South African experience.

BACKGROUND: The use of human bodies for anatomy education and research forms an integral part of the training of health professionals around the world. However, the ethical acquisition of human remains for this purpose has been a challenge in many countries, particularly for those on the African continent. South African institutions have however, been able to progressively transition to a more ethical approach to human body acquisition. The aim of the current study was to investigate the provenance of human bodies and the number used in South African health sciences institutions during the period 2017-2021. METHODS: an online self-administered anonymised questionnaire was circulated to all health sciences institutions in South Africa. Questions were focused on establishing the provenance and the associated number of bodies and body donor programmes. RESULTS: responses were received from thirteen of the fourteen South African institutions. All thirteen institutions use human bodies for teaching and research, with the majority of the institutions being reliant on bequests (77%) and family donations (62%), and less on unclaimed remains (46%). Most institutions have established body donor programmes. Four institutions were negatively affected by the effects of the pandemic. Memorial services, which continued during the pandemic, were conducted by eight of the thirteen institutions. CONCLUSION: South Africa is leading the transition to the ethical acquisition of human remains on the African continent. It is hoped that South African institutions will soon transform to the exclusive sourcing of bodies through willed donation and provide guidance and support for the other countries on the continent.

Neuropil Variation in the Prefrontal, Motor, and Visual Cortex of Six Felids.

INTRODUCTION: Felids have evolved a specialized suite of morphological adaptations for obligate carnivory. Although the musculoskeletal anatomy of the Felidae has been studied extensively, the comparative neuroanatomy of felids is relatively unexplored. Little is known about how variation in the cerebral anatomy of felids relates to species-specific differences in sociality, hunting strategy, or activity patterns. METHODS: We quantitatively analyzed neuropil variation in the prefrontal, primary motor, and primary visual cortices of six species of Felidae (Panthera leo, Panthera uncia, Panthera tigris, Panthera leopardus, Acinonyx jubatus, Felis sylvestris domesticus) to investigate relationships with brain size, neuronal cell parameters, and select behavioral and ecological factors. Neuropil is the dense, intricate network of axons, dendrites, and synapses in the brain, playing a critical role in information processing and communication between neurons. RESULTS: There were significant species and regional differences in neuropil proportions, with African lion, cheetah, and tiger having more neuropil in all three cortical regions in comparison to the other species. Based on regression analyses, we find that the increased neuropil fraction in the prefrontal cortex supports social and behavioral flexibility, while in the primary motor cortex, this facilitates the neural activity needed for hunting movements. Greater neuropil fraction in the primary visual cortex may contribute to visual requirements associated with diel activity patterns. CONCLUSION: These results provide a cross-species comparison of neuropil fraction variation in the Felidae, particularly the understudied Panthera, and provide evidence for convergence of the neuroanatomy of Panthera and cheetahs.

Variation, sexual dimorphism, and enlargement of the frontal sinus with age in adult South Africans.

OBJECTIVES: To document frontal sinus volume (FSV) in a sample of sub-Saharan Africans with a view to evaluating claims that such populations exhibit comparatively small sinuses. This study also addresses questions related to sexual dimorphism, incidence of sinus aplasia, and the possibility that FSV continues to increase through adulthood. MATERIALS AND METHODS: FSV was measured from CT scans of adult crania from the Dart Collection. Sex and age were known for each individual. Linear cranial dimensions were used to compute a geometric mean from which a scaled FSV was computed for each cranium. RESULTS: FSV does not differ significantly between sexes, but females exhibit a higher incidence of aplasia. There is considerable variation in FSV in this sample, with the average ranking among the higher means reported for other population samples. The incidence of FS aplasia falls within the range of values recorded for other population samples. Although our study is cross-sectional rather than longitudinal, there is strong evidence that FSV continues to increase with age throughout adulthood. DISCUSSION: The FSV mean of our sample contradicts the notion that sub-Saharan Africans possess small sinuses. In a global context, geography (climate and altitude) does not appear to be related to FSV. The absence of sexual dimorphism in our sample is unexpected, as significant dimorphism has been reported for most other population samples. Our results support other indications that the frontal sinus continues to expand throughout adulthood, especially in females, and that it is likely due to bone resorption.

Metopism in adult South Africans and its relationship to frontal sinus size.

This study documents the incidences of complete and partial metopism and their possible relationship to frontal sinus volume (FSV) in a sample of modern adult black South Africans with a view to evaluating the hypothesis that metopism affects frontal sinus hypoplasia. FSV was measured from CT scans and the incidence of metopism was recorded from direct observations of dried cadaveric crania. The sex of each individual was known. Four linear cranial dimensions were used to compute a geometric mean by which to scale FSV. The incidence of partial metopism (38%) is comparable to that reported for other population samples, although there is considerable variation among these global sample frequencies. It is significantly more common in male than female South Africans. FSV in individuals with complete metopism is smaller than average but not inordinately so. On the other hand, FSV is significantly larger in individuals with partial metopism than in those that do not present with this sutural remnant. The data on FSV in individuals with and without partial metopism contradict the hypothesis that there is a relationship between partial metopism and frontal sinus hypoplasia. As such, the metopic remnant evinced by the Late Pleistocene cranium from Hofmeyr, South Africa is unlikely to be related to its very small FSV.

Profiting from public dissection: A new era of unethical practices.

Historically, adverse events have reflected poorly on both the practice of dissection and the perception of the discipline of anatomy. The recent public dissection of a body donor is a regression to an unethical historical practice and was strongly denounced by anatomists around the world. The individual whose donated body was sourced from a 'for-profit" company in the United States had not given consent for a public dissection. This violates the ethics surrounding consent and body donation and potentially places the future of body donor programs in jeopardy as it compromises community frameworks around epistemic trust. Recent guiding frameworks by international anatomical associations on the ethical use of bodies have cemented the way in which body donor programs should operate. This viewpoint reflects on past and current events pertaining to public dissections and questions how these indignities may influence the public's interaction with human bodies. The authors argue that public dissection should be prohibited as it is against social mores. Social pressure should be applied to individuals or companies who wish to profit from unethical anatomical practice and legislation prohibiting public dissection should be introduced in those countries where it does not yet exist.

Sex estimation from dimensions of the base of the skull in Black South Africans.

The pelvis and the skull are the two most utilised skeletal elements to estimate sex from skeletonised remains due to their sexually dimorphic traits. However, as increasingly more fragmented remains have been presented for analyses, other bones and their fragments have now been subjected to analyses for sex estimation. In the skull particularly, the base has shown to survive harsh conditions. In this study the foramen magnum region was explored in Black South Africans to estimate sex during forensic analyses. Seven measurements of the foramen magnum and surrounding areas were measured in 120 male and female crania and subjected to discriminant function analyses. The average accuracies for the stepwise discriminant functions ranged from 60-71% whilst the average accuracies for the direct discriminant functions ranged from 63-69%. The average accuracies obtained in this study are similar to other studies performed using the foramen magnum. However, these average accuracies are much lower than other skeletal elements that have been used for sex estimation in South Africans. Thus, the equations in this study should be used with caution and only in the absence of more accurate elements. The cranial base has always shown to have a low to moderate expression of sexual dimorphism. The cranial base of Black South Africans is no different.

Nuclear organization and morphology of catecholaminergic neurons and certain pallial terminal networks in the brain of the Nile crocodile, Crocodylus niloticus.

In the current study, we use tyrosine hydroxylase (TH) immunohistochemistry to detail the nuclear parcellation and cellular morphology of neurons belonging to the catecholaminergic system in the brain of the Nile crocodile. In general, our results are similar to that found in another crocodilian (the spectacled caiman) and indeed other vertebrates, but certain differences of both evolutionary and functional significance were noted. TH immunopositive (TH+) neurons forming distinct nuclei were observed in the olfactory bulb (A16), hypothalamus (A11, A13-15), midbrain (A8-A10), pons (A5-A7) and medulla oblongata (area postrema, C1, C2, A1, A2), encompassing the more commonly observed nuclear complexes of this system across vertebrates. In addition, TH + neurons forming distinct nuclei not commonly identified in vertebrates were observed in the anterior olfactory nucleus, the pretectal nuclear complex, adjacent to the posterior commissure, and within nucleus laminaris, nucleus magnocellularis lateralis and the lateral vestibular nucleus. Palely stained TH + neurons were observed in some of the serotonergic nuclei, including the medial and lateral divisions of the superior raphe nucleus and the inferior raphe and inferior reticular nucleus, but not in other serotonergic nuclei. In birds, a high density of TH + fibres and pericellular baskets in the dorsal ventricular ridge marks the location of the nidopallium caudolaterale (NCL), a putative avian analogue of mammalian prefrontal cortex. In the dorsal ventricular ridge (DVR) of the crocodile a small region in the caudolateral anterior DVR (ADVRcl) revealed a slightly higher density of TH + fibres and some pericellular baskets (formed by only few TH + fibres). These results are discussed in an evolutionary and functional framework.

Secular trends in cranial size and shape among black South Africans over the late 19th and 20th centuries.

BACKGROUND: Previous studies of secular change in cranial size among black South Africans have produced conflicting results. AIM: We re-examined cranial size change in this population during the 19th and 20th century by evaluating its relationship with individual year-of-birth, and the significance of trends among eight decennial cohorts. SUBJECTS AND METHODS: This study is based on 102 male and 89 female adults born between 1865 and 1959. Linear regressions were employed to evaluate possible relationships between year-of-birth and cranial dimensions; ANOVAs were used to evaluate the significance of long-term trends among decennial cohorts. RESULTS: No analysis revealed a secular change in cranial length in either sex; however, the ANOVA for cranial length in the combined sex sample was significant. There is no secular trend in female cranial breadth, but males display a negative trend in this dimension. This results in a secular trend for increased male dolichocephaly. CONCLUSIONS: The factors that underlie the negative secular trend in male cranial breadth and the absence of a secular trend in overall cranial size in this population are unclear. Nevertheless, these observations accord with findings related to stature and long bone strength in this population and are consistent with observations for other sub-Saharan African populations.

Brain gyrification in wild and domestic canids: Has domestication changed the gyrification index in domestic dogs?

Over the last 15 years, research on canid cognition has revealed that domestic dogs possess a surprising array of complex sociocognitive skills pointing to the possibility that the domestication process might have uniquely altered their brains; however, we know very little about how evolutionary processes (natural or artificial) might have modified underlying neural structure to support species-specific behaviors. Evaluating the degree of cortical folding (i.e., gyrification) within canids may prove useful, as this parameter is linked to functional variation of the cerebral cortex. Using quantitative magnetic resonance imaging to investigate the impact of domestication on the canine cortical surface, we compared the gyrification index (GI) in 19 carnivore species, including six wild canid and 13 domestic dog individuals. We also explored correlations between global and local GI with brain mass, cortical thickness, white and gray matter volume and surface area. Our results indicated that GI values for domestic dogs are largely consistent with what would be expected for a canid of their given brain mass, although more variable than that observed in wild canids. We also found that GI in canids is positively correlated with cortical surface area, cortical thickness and total cortical gray matter volumes. While we found no evidence of global differences in GI between domestic and wild canids, certain regional differences in gyrification were observed.

Cervical Rib Synostosis to the First Rib: A Rare Anatomic Variation.

BACKGROUND: Congenital anatomic variations exist in human anatomy, which create both diagnostic and treatment challenges. Understanding the osteologic and radiographic anatomy of supernumerary ribs arising from the cervical spine and recognizing the morphologic variations thereof is of great importance to clinicians, radiologists, and surgeons alike. CASE DESCRIPTION: This case study describes osteologic morphology and radiologic characteristics of a rare anatomic variant of a cervical rib (CR): a unilateral, right-sided CR synostosis to the first thoracic rib of a 50-year-old South African man of African ancestry. The characteristic features included increased angulation, widening of the body, and shortening of the length of the right-sided first thoracic rib. The synostosis of the CR shaft was at the level of the angle of the first thoracic rib. The widest aspect of the first thoracic rib was close to the site of fusion, namely the angle, with the mediolateral length approximately 34.51 mm. This is in contrast to the contralateral first thoracic rib measuring, at its widest, 26.39 mm. The CR was located approximately 3.34 mm superiorly to the first thoracic rib at the cervical articular facet. The CR presented with a well-defined head, which is small and rounded with the inclusion of an articular facet. Thereafter, it presented with a short neck, just over half the length of the inferiorly placed first thoracic rib, and a similar sized articulating facet at the tubercle. The appearance of the trabecular bone pattern on radiographs is in keeping with the contralateral left first rib, although altered in accordance with the gross osteologic appearance described earlier. Furthermore, the radiographs highlight an elliptical lucent-zone within the trabecular bone demonstrating decreased density centrally with a thin rim of sclerotic cortical bone peripherally. This is consistent with classical rib architecture in cross-section representing the CR shaft site of fusion to the first thoracic rib. The CR synostosis to the first thoracic rib represents a novel complex, termed by the authors as a cervicothoracic rib complex. CONCLUSION: The present report refers to the osteologic and radiographic description and comparison of a unilateral, right-sided CR synostosis to a first thoracic rib. The clinical implications of CRs may consist of neurologic, vascular complications, and functional deficits of the involved limb associated with thoracic outlet syndrome (TOS). A CR synostosis to the first thoracic rib represents an associated increased risk of vascular injury, with poorer operative outcomes associated with TOS. This case study is of particular importance to vascular surgeons and neurosurgeons involved with surgical planning and intervention strategies relating to CRs and TOS.

A three-dimensional digital atlas of the Nile crocodile (Crocodylus niloticus) forebrain.

The phylogenetic position of crocodilians in relation to birds and mammals makes them an interesting animal model for investigating the evolution of the nervous system in amniote vertebrates. A few neuroanatomical atlases are available for reptiles, but with a growing interest in these animals within the comparative neurosciences, a need for these anatomical reference templates is becoming apparent. With the advent of MRI being used more frequently in comparative neuroscience, the aim of this study was to create a three-dimensional MRI-based atlas of the Nile crocodile (Crocodylus niloticus) brain to provide a common reference template for the interpretation of the crocodilian, and more broadly reptilian, brain. Ex vivo MRI acquisitions in combination with histological data were used to delineate crocodilian brain areas at telencephalic, diencephalic, mesencephalic, and rhombencephalic levels. A total of 50 anatomical structures were successfully identified and outlined to create a 3-D model of the Nile crocodile brain. The majority of structures were more readily discerned within the forebrain of the crocodile with the methods used to produce this atlas. The anatomy outlined herein corresponds with both classical and recent crocodilian anatomical analyses, barring a few areas of contention predominantly related to a lack of functional data and conflicting nomenclature.

Secular decline in limb bone strength among South African Africans during the 19th and 20th centuries.

OBJECTIVES: South African Africans have been reported to have experienced negative or null secular trends in stature and other measures of skeletal structure across the 19th and 20th centuries, presumably due to poor living conditions during a time of intensifying racial discrimination. Here, we investigate whether any secular trend is apparent in limb bone strength during the same period. MATERIALS AND METHODS: Cadaver-derived skeletons (n = 221) were analyzed from female and male South African Africans who were born between 1839 and 1970, lived in and around Johannesburg, and died between 1925 and 1991 when they were 17-90 years of age. For each skeleton, a humerus and femur were scanned using computed tomography, and mid-diaphyseal cross-sectional geometric properties were calculated and scaled according to body size. RESULTS: In general linear mixed models accounting for sex, age at death, and skeletal element, year of birth was a significant (p < .05) negative predictor of size-standardized mid-diaphyseal cortical area (a proxy for resistance to axial loading) and polar moment of area (a proxy for resistance to bending and torsion), indicating a temporal trend toward diminishing limb bone strength. No significant interactions were detected between year of birth and age at death, suggesting that the decline in limb bone strength was mainly due to changes in skeletal maturation rather than severity of age-related bone loss. DISCUSSION: Limb bone strength is thus potentially another feature of the skeletal biology of South African Africans that was compromised by poor living conditions during the 19th and 20th centuries.

The Law, Ethics and Body Donation: A Tale of Two Bequeathal Programs.

Historically, legislature has been utilized to facilitate appropriate use of cadavers in the anatomical sciences. However, cadaver acquisition and use have also been guided by ethically appropriate and morally acceptable principles. Various global and regional frameworks of "ethical practice" guide body donation, including the use of unclaimed bodies by institutions. These frameworks are responsive to, and reciprocal with the various ethical, moral and legal factors that influence the development of body donation programs. This reciprocity supports the notion that anatomists and anatomical societies have a responsibility to advocate for legal reform when required. In this study, two body bequest programs from geopolitically and socially disparate countries are used as cases to contrast existing legal and governance frameworks for body donation and to examine whether anatomists can direct the acquisition of ethically donated cadavers. The study includes an Australian donor program that has exclusively accepted bequests since its inception, and a South African program that has recently transitioned to a bequest system. Elements such as consent by next-of-kin and Inspector of Anatomy, use of unclaimed bodies and ethics committee approval amongst others, are compared. It is acknowledged that legal frameworks for cadaver acquisition generally deliver broad guidance on acceptable utilization of bodies for the anatomical sciences. However, professional discretion is of importance in adapting to societal needs and values. Thus, while anatomists have been able to progress toward more ethical practice than that which is required by the law, they must continue to do so as societal values evolve.

Development of discriminant functions to estimate sex in upper limb bones for mixed ancestry South Africans.

South Africa has one of the highest murder rates in the world, which is associated with an increasing number of unidentified individuals. Forensic anthropologists can assist in these cases to reduce the number of potential victims the remains may belong to. Sex estimation potentially decreases the number of possible victims by half. The mixed ancestry population in South Africa is the second largest group of people; however, there remains a paucity of data and population-specific methods for sex estimation in this group. The aim of this study was to assess the potential for metrices obtained around the nutrient foramen and the maximum length of upper limb long bones to estimate sex in mixed ancestry South Africans using discriminant function analysis. A total of 328 humeri, radii and ulnae from individuals of mixed ancestry were analysed. Sex was correctly classified with an average classification accuracy of 84.3% in the humeri, 88.3% for radii and 83.5% for the ulnae. Total length was the single best predictor of sex; the combination of total length with dimensions related to the nutrient foramen produced high classification accuracies in the current study. Overall, sexual dimorphism was observed in mixed ancestry South Africans upper limb long bones. The findings of this study further emphasise the need for population-specific standards of sexing in an attempt to improve current methods of forensic identification of descendants.

Myositis ossificans traumatica of the piriformis muscle: a rare mature case in an adult African male.

Myositis ossificans traumatica (MOT) is a common form of heterotopic ossification associated to trauma. Rare mature manifestations and topographically atypical presentations of MOT are often misdiagnosed as osteosarcoma. This case study discusses a rare, mature case of MOT of the piriformis muscle, potentially clinically associated with piriformis syndrome. The ossification was observed on a dry sacral bone of an adult skeleton belonging to a South African male during routine inventory of the Raymond A. Dart Collection of Human Skeletons, the University of the Witwatersrand, Johannesburg. The MOT was located on the anterior aspect of the sacrum at a site corresponding to the upper portion of the origin of the muscle and extended laterally towards the greater trochanter, beyond the greater sciatic notch. It was cylindrical in shape and measured approximately 52.70 mm in length and 12.10 mm in diameter. Micro-focus CT revealed an extensive and mature bony development of the piriformis muscle with distinct outer cortical and inner trabecular bone. In addition, the skeleton showed widespread healed skeletal trauma, suggesting a history of trauma. The MOT was completely fused to the sacral bone excluding the possibility of congenital anomalies. Information on the MOT of the piriformis muscle is vital to clinicians and radiographers to aid in successful diagnosis and management of the piriformis syndrome and sciatica in the gluteal region. This case also provides a rare example to biological anthropologists, paleoanthropologists and bioarchaeologists of the representation of pathologies like these on a dry bone sample.

Making the Ethical Transition in South Africa: Acquiring Human Bodies for Training in Anatomy.

While dissection remains the method of choice for teaching human anatomy, ethical requirements for obtaining cadavers has made the process of acquiring human bodies more strenuous for institutions. In Africa and at the School of Anatomical Sciences in South Africa, dependence on unclaimed bodies has been prevalent. The aim of the present study was to determine whether more rigorous application of ethical consent has altered the provenance of the cadavers in the School of Anatomical Sciences, University of the Witwatersrand. The numbers of bequeathed/donated/unclaimed cadavers received over the period 2013-2017, as well as their sex and population affinity were analyzed. The majority (96.8%) of the cadavers dissected over the period were from bequests/donations. Marginally more females than males were available. In addition, the population affinity of the cadavers had changed from a majority of South African African (unclaimed) bodies to a majority of South African White (bequest/donated) bodies. The study shows that even with ethical constraints it is possible to transition from the use of mainly unclaimed bodies to the acquisition of bequeathed/donor bodies. However, there may be challenges in relation to anatomical collections in the School as few of the bequest/donated cadavers remain in the School to be added to the collections. These changes also affect the demographics of the Schools' collections.

Dimensions around the nutrient foramina of the tibia and fibula in the estimation of sex.

Sex estimation from skeletal remains is one of the key components in establishing a biological profile and consequent identification of an individual in a forensic and medico-legal practice. The use of dimensions around the nutrient foramen in instances where long bones may be fragmented and damaged is of benefit due to the fact that the nutrient foramen is easily identifiable and may be preserved on the shaft of long bones. This study is an investigation of the usefulness of various measurements around the nutrient foramen of the tibia and fibula of South Africans in an attempt to develop osteometric standards for sex estimation. The sample included 206 tibiae and 204 fibulae of South African Africans (SAA) and South African whites (SAW) procured from the Raymond A. Dart Collection of Human Skeletons based at the University of the Witwatersrand. Sex was correctly classified for the tibia with an accuracy ranging between 79-82% in SAA and 84-88% in SAW, with the circumference at the level of the nutrient foramen as the single best predictor of sex in both populations. An accuracy ranging from 69 to 74% in SAA and 70-77% in SAW was observed for the combined measurements on the fibula. The current study confirms the usefulness of measurements around the nutrient foramen of the tibia in the assignment of sex. However functions of the fibula generally performed poorly and should be used with caution.

Functional MRI in the Nile crocodile: a new avenue for evolutionary neurobiology.

Crocodilians are important for understanding the evolutionary history of amniote neural systems as they are the nearest extant relatives of modern birds and share a stem amniote ancestor with mammals. Although the crocodilian brain has been investigated anatomically, functional studies are rare. Here, we employed functional magnetic resonance imaging (fMRI), never tested in poikilotherms, to investigate crocodilian telencephalic sensory processing. Juvenile Crocodylus niloticus were placed in a 7 T MRI scanner to record blood oxygenation level-dependent (BOLD) signal changes during the presentation of visual and auditory stimuli. Visual stimulation increased BOLD signals in rostral to mid-caudal portions of the dorso-lateral anterior dorsal ventricular ridge (ADVR). Simple auditory stimuli led to signal increase in the rostromedial and caudocentral ADVR. These activation patterns are in line with previously described projection fields of diencephalic sensory fibres. Furthermore, complex auditory stimuli activated additional regions of the caudomedial ADVR. The recruitment of these additional, presumably higher-order, sensory areas reflects observations made in birds and mammals. Our results indicate that structural and functional aspects of sensory processing have been likely conserved during the evolution of sauropsids. In addition, our study shows that fMRI can be used to investigate neural processing in poikilotherms, providing a new avenue for neurobiological research in these critical species.

Sex estimation using dimensions around the nutrient foramen of the long bones of the arm and forearm in South Africans.

South Africa has had an increase in rates of crime, interpersonal violence and homicide since the introduction of democracy in 1994. Forensic osteological standards was lacking for South Africans of different population groups necessitating the generation of new standards for forensic identification of individuals from skeletal remains. For these reasons, there is a concerted demand for methods of identifying skeletal remains with sex being amongst the most important of the biological characteristics required. The nutrient foramen has been used to estimate sex in lower limb long bones with much accuracy but this has not been demonstrated in the upper limb long bones. The aim of this study was to develop osteometric standards for sex estimation from measurements around the nutrient foramen of the arm and forearm bones of South Africans of different population affinities. A total of 660 bones consisting of humeri, radii and ulnae of black South Africans and white South Africans were assessed for sex estimation using dimensions related to the nutrient foramen. Sex was correctly classified with a range of 84-85% for the humerus and 83-88% for the arm bones. The study showed that length measurements were more sexually dimorphic than width dimensions in South Africans, as length was consistently selected as the best predictor of sex in all bones. However, the average accuracy increased when length was used in combination with measurements related to the nutrient foramen. In conclusion, the dimensions of upper limb long bones that are directly related to the nutrient foramen are sexually dimorphic and are useful in the estimation of sex in South Africans, with the highest accuracy shown in the white South African population group.